Fungi in the sun

How mushrooms connect everything in nature

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The so-called “earthstar” fungus genus Astreaus closes up when it’s dry and opens when there’s more rain.
Courtesy of Andrew Wilson

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s the warm days of summer set in and the Earth grows more vibrant by the day, stop and take a moment to consider a story about the interconnectedness of nature.

The tale starts with the symbiotic love affair between plants and mushrooms that bloomed nearly 5 million years ago, according to Jennifer Frazer, a freelance science writer who leads the Scientific American blog “The Artful Amoeba” from her home in Superior, Colorado.

“Every indication that we have from fossils is that [plants and mushrooms] colonized land together. It was a team effort,” she says.

She explains that our human existence is due in part to fungi (officially pronounced FUN-jai). Without the sometimes slimy, sometimes stinky organisms, Frazer says Earth would stand no chance of supporting its array of animals and plants. In other words, in a world without mushrooms, we’d all be dead.

At the moment, we have an abundance of fungal friends operating the soil of Colorado’s plains, foothills and mountains. Too many to count, in fact, says Dr. Andrew Wilson of Denver’s Botanic Gardens, who estimates we know potentially less than 5 percent of the total estimated diversity on the planet. He confesses: “If we talk about a scale of one to 10 on what we know [about mushrooms], we might have just bumped up to a two,” and then adds that if we were to try documenting the rest of the fungal species, it would probably take a millennium to get them all down.

Despite this daunting drought of knowledge, Wilson has made fungal diversity the center of his life’s research. His work has taken him all over the globe and led to his appointment as the Gardens’ assistant curator of mycology earlier this year.

In the Botanic Gardens’ Sam Mitchel Herbarium of Fungi, Wilson rolls a giant row of mushroom specimens along a track. He’s hoping to show off one of his favorite fungi: the “puffball” genus Astreaus.

A single row in the herbarium, which contains one of the most actively curated and diverse collections in the Rocky Mountain region, contains up to 12 cabinets, each with 24 bins. One bin holds a box containing up to 50 specimens, which are catalogued and organized according to the specimen’s genus.

Of the nearly 20,000 different kinds of “mushroom mummies” held in the lab, Wilson’s favored Astreaus collection is special because of how it’s evolved to react to atmospheric moisture. When it’s dry out, as it often is in Colorado, the so-called “earthstar” fungus will close up its petal-like structure to protect its fragile puffball — a spherical house for its spores. Mushrooms need moisture to survive, so this opening and closing mechanism developed as a survival tool for fungi living in arid climates. When the climate is once again hospitable, the earthstar opens like a flower in order to disperse its spores.

“What I do is kind of like a forensic investigator,” Wilson says. “I take the molecular evidence, like the scene of a crime, to reconstruct what happened.”

He’s talking about the diversity and evolution of mushrooms; Wilson specializes in using DNA and genome sequencing technologies to understand how fungi evolve — like why the puffball became a puffball. This is important in his line of work because the more we understand how and why mushrooms evolve the way that they do, the more we can understand changes occurring in local ecologies and the environment.

In many ways, both Wilson and Frazer act as representatives for the “fungal nation,” a sort of underground heartbeat for Mother Earth.

“My role as a scientist,” Wilson says, “is to try and communicate what’s going on in nature.”

Turns out, there’s a lot going on that took humans years to catch on to.

In her blog, Frazer writes, “Forest trees and their root fungi are more or less a commune in which they share resources in a fashion so unabashedly socialist that I hesitate to describe it in detail lest conservatives reading this go out and immediately set light to the nearest copse.”

“There’s a huge group of fungi called the mycorrhizal network that partner with plant, tree and grass roots to help them acquire minerals and water,” she explains in person. “Plants and trees aren’t great at harvesting those alone. In exchange, plants give fungi food.”

In addition to this nutrient trade-off, plants can also use the mycorrhizal network to communicate. As Wilson says, “Trees of different species work in cooperation with each other in the forest.” One tree can produce sugars from photosynthesis, and the fungi can transport those sugars to a different tree. “Fungi are the conduit that help these trees stay connected.”

In Colorado, this looks like what happened in the 2000s, when the mountain pine beetle came to town and the lodgepole pine wasn’t ready to defend itself against these invaders. The pine’s underground neighbors, like the white king bolete mushroom, can feel the alarm reverberating through the tree’s sugar. So they stand at attention and deliver extra nutrients upstairs so the pine can concoct defensive chemicals that help ward off attacks. (In the case of this unprecedented-in-human-time beetle attack, rarely was this enough. A devastating amount of trees died, and many mushrooms, too — overworked, starved and exhausted. The specter of global warming does not discriminate.)

Magic aside, this symbiotic relationship is vital to the livelihood of at least 90 percent of herbaceous organisms.

“If the fungi leave, probably the vast majority of terrestrial life on the planet will die,” Wilson says.

And we know what happens if plants die: we die.

This is especially important to note in places like Colorado, where arid climates, high elevation and cold temperatures can already make life for mushrooms a trying ordeal. The burning of slash piles to help mitigate wildfires also creates problems for mushroom life in Colorado.

Wilson explains that when these piles are burned, they produce so much heat that it sterilizes the soil up to four feet beneath it. Nutrients like nitrogen, which are essential to the health of both fungi and trees, become volatilized and dispersed into the atmosphere.

“The losses in diversity that ensue take a long time to recover,” he says.

These are practices that mycologists need time, and funding, to research. As both Wilson and Frazer highlight in their work, tree, plant and mushroom diversity is paramount to the health of our ecologies, and can give us helpful clues for the best conservation practices, thus how to keep our own species alive.

“Here in the Rocky Mountains we have this incubator playground to explore a lot of these questions,” Wilson says. “Compared to other landscapes, the sheer amount of undisturbed and preserved habitat makes it special.”

Instead of running around trying to fill in the 95 percent knowledge gap (although he does do a bit of that), Wilson tends to favor the big questions:

How much do we want to focus on documenting biodiversity as opposed to documenting what is all this biodiversity doing to the planet? How do the changes in the ecosystems today affect the fungal communities that are likely very important for the sustainability of the ecosystems?

“As we’re becoming more and more cognizant of our human impact on the planet,” Wilson says, “we want to understand what is necessary to preserve or restore habitats. Understanding what’s happening to the soil communities, and specifically fungi, is going to be critical in maintaining and engaging in conservation and restoration practices.”

Though the plant-mushroom affair started millions of years ago, both Wilson and Frazer are still negotiating the story of the plant-mushroom-human relationship. Once the snow fully melts and the fungi pop back up, Wilson will start his first official Rocky Mountain foraging season, and will spend the next five months collecting data, hopefully reducing our knowledge deficit from 95 percent to 94.9 percent.

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